Why is my union going in the ground when using SubtractAsync()?

Hello everyone,

So I have a little problem here. I’m trying to negate a part using SubtractAsync() to create a new unioned part, but for some reason when I run the code the union gets split and one part of it gets stuck in the baseplate like exactly this. I’ve never had this problem before, as SubtractAsync() usually worked fine with me but this is news to me. Do you know what I did wrong or how to fix this? Also to note, a union is negating the part through SubtractAsync(), so it is going from union to being a union again through SubtractAsync(). Hope that helps. Here is my code. It’s relatively simple.

	local negativePart = Instance.new("Part")
		negativePart.Size = Vector3.new(10, 150, 200) 
		negativePart.CFrame = oldCFrames[i] + Vector3.new(0,5.8,0) -- 5.88
		negativePart.Anchored = true
		negativePart.Name = "NegationPartFinal"
		
		negativePart.Transparency = 0

		negativePart.Parent = workspace
		
		wait(3)
		
		local newUnion = unionP:SubtractAsync({negativePart})

-- Where unionP is the old union being negated with negativePart

Thanks a lot.

Anyone please help? Thanks. I appreciate it.

Have you solved the problem yet? I am experiencing it too